title: Histone deacetylase inhibitors increase microRNA-146a expression and enhance negative regulation of interleukin-1β signaling in osteoarthritis fibroblast-like synoviocytes.
abstract: OBJECTIVE
  MiR-146a exerts negative control on inflammatory responses by suppressing cytokine-induced expression of interleukin-1 receptor-associated kinase-1 (IRAK1) and tumor necrosis factor receptor-associated factor 6 (TRAF6) by impairing NF-κB activity and inhibiting the expression of target genes. Recent study suggests that histone deacetylases (HDACs) are involved in the regulation of microRNA (miRNA) expression. Therefore, we determined whether HDAC inhibitors can increase miR-146a expression, thereby inhibiting interleukin-1β (IL-1β)-induced signaling in osteoarthritis fibroblast-like synoviocytes (OA-FLS).
  
  
  METHODS
  MiRNA expression was analyzed using real-time PCR. IL-1β-induced downstream signals and cytokine expression were evaluated using Western blotting and ELISA. Transcription factors regulating promoter activation were identified using chromatin immunoprecipitation assays.
  
  
  RESULTS
  IL-1β treatment of OA-FLS induced a mild (1.7-fold) increase in miR-146a expression that was unable to appropriately downregulate IRAK1 and TRAF6 expression. HDAC inhibitors, SAHA (vorinostat), and LBH589 (panobinostat) significantly (6.1- and 5.4-fold) elevated miR-146a expression by increasing the binding of the transcription factor NF-κB to the miR-146a promoter, and negatively regulated IL-1β-induced IKK/IκB/p65 phosphorylation signaling and IL-6 secretion. The increase in miR-146a expression induced by the HDAC inhibitors was prevented by transfection of miR-146a inhibitor or HDAC1 (class I HDAC), HDAC4 (class IIa HDAC), and HDAC6 (class IIb HDAC) overexpression, suggesting that they were due to inhibition of HDAC activity.
  
  
  CONCLUSIONS
  Our study demonstrated that HDAC inhibitor treatment in OA-FLS significantly increased miR-146a expression and mediated markedly negative regulation to inhibit IL-1β-induced signaling and cytokine secretion. Our results indicate the potential rationale of anti-inflammatory effects for HDAC inhibitors.
authors.affiliation: Department of Orthopedic Surgery, National Taiwan University Hospital, Taipei 10051, Taiwan.
authors.forename: J H
authors.initials: JH
authors.lastname: Wang
authors.forename: K S
authors.initials: KS
authors.lastname: Shih
authors.forename: Y W
authors.initials: YW
authors.lastname: Wu
authors.forename: A W
authors.initials: AW
authors.lastname: Wang
authors.forename: C R
authors.initials: CR
authors.lastname: Yang
mesh_terms: D016022:Case-Control Studies; D002478:Cells, Cultured; D005347:Fibroblasts / Q000187:drug effects* / Q000276:immunology; D015870:Gene Expression / Q000187:drug effects; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology*; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology; D053592:Interleukin-1 Receptor-Associated Kinases / Q000187:drug effects / Q000276:immunology; D053583:Interleukin-1beta / Q000187:drug effects* / Q000276:immunology; D035683:MicroRNAs / Q000187:drug effects* / Q000235:genetics / Q000276:immunology; D016328:NF-kappa B / Q000187:drug effects / Q000378:metabolism; D010003:Osteoarthritis / Q000276:immunology*; D000077767:Panobinostat; D011401:Promoter Regions, Genetic; D015398:Signal Transduction / Q000187:drug effects* / Q000276:immunology; D013583:Synovial Membrane / Q000166:cytology* / Q000187:drug effects / Q000276:immunology; D048029:TNF Receptor-Associated Factor 6 / Q000187:drug effects / Q000276:immunology; D000077337:Vorinostat
chemical_list: D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; C508585:IL1B protein, human; D007211:Indoles; D053583:Interleukin-1beta; C542542:MIRN146 microRNA, human; D035683:MicroRNAs; D016328:NF-kappa B; D048029:TNF Receptor-Associated Factor 6; D000077337:Vorinostat; D000077767:Panobinostat; C507768:IRAK1 protein, human; D053592:Interleukin-1 Receptor-Associated Kinases
keywords: Histone deacetylase; Interleukin-1; Interleukin-1 receptor-associated kinase-1; MicroRNA; Tumor necrosis factor receptor-associated factor 6